After injury to an ankle, such as a fracture or severe sprain thereof, it is often necessary to completely immobilize the injured ankle through the use of a molded plaster or resin cast. Once the injury has been stabilized, however, recovery may be accelerated by removing the molded plaster or resin cast and replacing it with a removable functional walking brace so that the ankle can be exercised while healing.
Even if the injury is not severe enough to warrant complete immobilization of the ankle, it is still sometimes necessary to use a functional walking brace to stabilize the ankle against inversion (the foot rolling inward), eversion (the foot rolling outward) and/or anterior subluxation (partial dislocation) while still allowing the normal dorsiflexion and plantarflexion movements of the ankle.
A variety of ankle braces, walking casts and other orthopaedic ankle apparatuses have previously been proposed. For instance, in T. E. Grim, U.S. Pat. No. 4,977,891 ('891), an ankle brace comprising two relatively rigid side supports with inflatable bladders attached to them is described. The side supports are connected at their bottom by a flexible strap upon which is mounted an air pump. The air pump is activated by walking and running, and it causes the air bladders mounted on the side supports to inflate. The side supports are held firmly in place about the lower leg and ankle by straps. A relief valve and/or pin holes in the bladders prevent excessive pressure in the bladders and provide reduced support when the user is inactive. While this arrangement prevents undesired eversion, inversion and anterior subluxation caused by activity, it also allows for reduced pressure during rest periods.
Other ankle braces which have air inflatable bladders are shown in G. W. Johnson, Jr.'s U.S. Pat. Nos. 4,280,489 and 4,628,945. These prior art devices are intended to be worn within a separate shoe and are also inflatable with an external source of air pressure or they are preinflated.
Other arrangements have been proposed to promote healing of an injured foot, ankle and/or lower leg, as shown in C. G. Eischen, Sr., U.S. Pat. No. 4,805,601 in which the apparatus includes a bladder which completely encircles the ankle, connected by an opening to a bladder underlying the foot. In addition, various arrangements have been proposed for ventilating shoes by circulating air through the shoes. Typical patents showing this type of arrangement include M. Dunker, U.S. Pat. No. 2,552,711; D. W. Oltrogger, U.S. Pat. No. 2,560,591; A. C. Crawford, U.S. Pat. No. 2,676,422; C. N. Eaton, U.S. Pat. No. 3,029,530; E. Karras, U.S. Pat. No. 3,331,146; and J. Faiella, U.S. Pat. No. 4,414,760. These patents disclose the use of air pumping arrangements actuated by foot pressure for circulating air through a shoe. Reference is also made to German publication designated Offenlegungsschrift No. 2321817, published Nov. 15, 1973, which publication shows a ski boot with inflatable ankle bladders, a rigid sole and a pump mounted in the sole. The pump can be latched to an inactive state when the inflatable pads are pressurized.
The prior art walking braces set forth above do not stabilize the ankle against anterior subluxation and permit plantarflexion and dorsiflexion while simultaneously increasing venous and lymphatic circulation and reducing swelling in the lower leg extremity by exercising the muscle groups of the lower leg. Thus, a principal object of the present invention is to effectively accomplish all of these functions.